Juntos Against Alcohol Tobacco and Drug Use Intervention Trial ABSTRACT Drug use by youth is a major public health concern in the United States (US). This is particularly true of Latino youth whose alcohol, tobacco, and other substances (ATOD) use 1.5 to 2 times higher than Whites. Although several programs have been developed to address Latino ATOD use, they rely on bilingual professionals with a Master's degree or higher to deliver the program. Latino families are increasingly locating themselves in new settlement areas that lack bilingual ATOD counselors equipped to provide appropriate prevention or treatment. This suggests that health disparities will widen without novel and effective ATOD use interventions targeting young Latino adolescents. Juntos is a positive youth development program that works with Latino parents and their adolescent children to delay or reduce ATOD use by increasing parental involvement in their child's schooling and youth academic achievement. Because Juntos can be delivered by community-based promotoras rather than masters level clinicians, it addresses the implementation, scalability and sustainability problems associated with existing ATOD prevention programs. Initial evaluations of Juntos' impact on strengthening Latino adolescents' ability to succeed in are positive, but its impact on reducing ATOD use has not been evaluated. The proposed project examines the preliminary efficacy of Juntos to decrease ATOD use among Latino youth in new settlement areas. The goals of this efficacy trial will be achieved by accomplishing two specific aims: 1.) Determine the potential efficacy of Juntos to delay initiation and reduce escalation of ATOD use; and 2.) Explore differences in stress exposure between Juntos and control group participants using an objective indicator of cumulative stress burden (allostatic load). Accomplishing these aims is significant because: (a) ATOD use poses a major burden on society and results in substantial impairment to adolescents; (b) it focuses on adolescents of immigrant Latinos, a segment of the population with elevated risk of substance abuse; and (c) if effective, it will provide evidence of treatment crossover effects for preventing or mitigating substance use with a program primarily focused on academic enhancement. The proposed project is innovative, in that it: (a) targets Latino immigrant youth and families in a new settlement community: an understudied population; (b) focuses on academics rather than drug use, which is more acceptable to parents and school officials; (c) tests the effects of a prevention program on reducing exposure to stress; and (d) is a community- rather than professional-based program: community volunteers deliver and support the program, thereby contributing to program sustainability in new settlement areas.